But that's not a belly -- those are the abs of a girl who obviously busts her booty at the gym! Or at least one who is genetically blessed...

After rocking a pair of sexy thigh high boots earlier in the evening, Rihanna slipped into something a bit more comfortable when we snapped her out and about in New York City on Monday night.

And speaking of sexy, the 24-year-old R&B superstar will perform her new hit single "Diamonds" at the Victoria's Secret Fashion Show, which will air on December 4, 2012. "Diamonds" is currently number one in 26 countries ... not to shabby!